Crystallographic and Spectroscopic Snapshots of Multi‐Stimuli‐Responsive Dinuclear Cobalt Metal−Organic Frameworks

• Published in: Advanced optical materials 2024-04, Vol.12 (11), p.n/a
• Main Authors: Li, Shu‐Fan, Ke, Si‐Wen, Wu, Miaomiao, Zuo, Jing‐Lin, Su, Jian, Zhang, Gen
• Format: Article
• Language: English
• Subjects: Carboxylates; Controllability; Coordination; Crystallography; Diffraction; dynamic coordination bond; Metal-organic frameworks; metal–organic framework; multi‐stimulus responsive; reversible transformation; Single crystals; Stimuli; Synchrotron radiation; Synthesis; two‐step SC‐to‐SC; Water chemistry
• ISSN: 2195-1071; 2195-1071
• DOI: 10.1002/adom.202302309

Investigating the reversible structural transformation of stimuli‐responsive metal–organic frameworks (MOFs) through single‐crystal diffraction and establishing a structure–property relationship pose a significant challenge. Herein, the controllable synthesis of Co‐MOF‐1 and Co‐MOF‐2 by incorporating water into the solvothermal synthesis process is presented. In comparison to the trinuclear [Co3(COO)8]2− clusters found in Co‐MOF‐1, Co‐MOF‐2 presents a variable dinuclear [Co2(COO)4(H2O)5] cluster. Single crystal diffraction studies, utilizing synchrotron radiation, confirm the reversible two‐step transformation. The presence of various organic solvents induces the single‐crystal‐to‐single‐crystal (SC‐to‐SC) transformation of Co‐MOF‐2. This transformation is initiated by the cleavage of three coordinated water molecules and subsequent coordination of carboxylates in the ligand, resulting in solvatochromic behavior. Further, the reversible stimuli‐responsive behavior can also be rapidly induced under the stimuli of heat, vacuum, and X‐rays. This study successfully demonstrates the crystallographic and spectroscopic snapshots of dynamic coordination bonds in MOFs and contributes to a deeper understanding of the structure–property relationship. Based on the dynamic coordination bond of dinuclear cobalt clusters, the breakage/formation of coordination bonds between cobalt ions and H2O/carboxylic acids is realized. Structural analysis of snapshots during the solvatochromic reaction reveals a two‐step‐SC‐to‐SC reversible structural transformation. As a multi‐stimuli‐responsive MOF, this transformation can also be achieved under the stimulation of heat, vacuum, and X‐rays.